﻿using System;
using System.Windows.Data;
using System.Windows.Markup;

namespace MyCalManager.Helper
{


    /// <summary>
    /// Base Class for ValueConverters 
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public abstract class ValueConverterBase<T> : MarkupExtension, IValueConverter where T : class, IValueConverter, new()
    {
        private static T _converter = null;

        public ValueConverterBase()
        {

        }

        /// <summary>
        /// When implemented in a derived class, returns an object that is set as the value of the target property for this markup extension.
        /// </summary>
        /// <param name="serviceProvider">Object that can provide services for the markup extension.</param>
        /// <returns>
        /// The object value to set on the property where the extension is applied.
        /// </returns>
        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            if (_converter == null)
            {
                _converter = new T();
            }
            return _converter;
        }

        #region IValueConverter Members

        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value produced by the binding source.</param>
        /// <param name="targetType">The type of the binding target property.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        public abstract object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture);

        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value that is produced by the binding target.</param>
        /// <param name="targetType">The type to convert to.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        public abstract object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture);

        #endregion
    }

}
